Radio frequency systems commonly employ filters in various applications. For example, resonating filters are used in the DC biasing of RF power amplifiers to prevent RF signals from propagating toward the DC bias sources where the RF energy would be wasted.
To improve the performance of such RF amplifiers, it is generally desirable to position these resonating filters as close to the RF amplifier as possible, as this can reduce the impedances between the RF amplifier and the RF resonating filter. Additionally, it is generally desirable to precisely tune the RF resonating filter to effectively block one or more specific frequencies. For example, it is generally desirable to block the main RF operational frequency of interest and one or more harmonics from propagating to the DC bias source. When an RF amplifier is properly configured with such RF resonating filters blocking the propagation of RF signals toward the DC bias sources, the overall bandwidth and performance of the RF amplifier can be improved.
Unfortunately, previous RF resonating filters implementations have had limited ability to achieve the bandwidth and precise frequency tuning needed effectively block multiple frequencies. For example, previous RF resonating frequencies have been limited in ability to block both the main RF operational frequency of an RF amplifier and one or more harmonics. For this and other reasons there remains a continuing need for improved resonating filters.